Abstract: An electronic device includes a front frame, a back cover, a support stand rotatably connected to the back cover, a display panel and a circuit board. The display panel and the circuit board are fixed between the front frame and the back cover. The circuit board includes a first contact and a number of second contacts. The second contacts surround the first contact. The support includes a central shaft and a third contact. The central shaft is electrically connected to the first contact. The third contact rotates with the rotation of the central shaft to contact each of the second contacts. The circuit board includes a circuit and a processor. The electric circuit generates different signals when the first contact is connected different second contacts. The processor adjusts an orientation of display content on the display panel to rotate based on the signal.

Abstract: A charging control circuit includes a switch circuit, a charging circuit, a central processing unit (CPU), and an identification circuit including two monitoring points for being connected to a first or second electronic device, and a mechanical switch connected between the two monitoring points. When charging the first electronic device, the mechanical switch switches to a first state where a voltage drop is generated on the two monitoring points respectively, and the switch circuit is turned on. When charging the second electronic device, the mechanical switch switches to a second state where the connection between the two monitoring points is short circuit, and the switch circuit is turned off. The CPU enables the charging circuit when the switch circuit is turned on or off to provide power to the first or the second electronic device via the charging unit.

Abstract: An electronic device includes a front frame, a back cover, a support stand rotatably connected to the back cover, a display panel and a circuit board. The display panel and the circuit board are fixed between the front frame and the back cover. The circuit board includes a first contact and a number of second contacts. The second contacts surround the first contact. The support includes a central shaft and a third contact. The central shaft is electrically connected to the first contact. The third contact rotates with the rotation of the central shaft to contact each of the second contacts. The circuit board includes a circuit and a processor. The electric circuit generates different signals when the first contact is connected different second contacts. The processor adjusts an orientation of display content on the display panel to rotate based on the signal.

Abstract: A switching power supply with output ripple suppression includes a rectification circuit, a filtering circuit, a PFC, a transformer, a voltage stabilization circuit and a DC/DC converting circuit with feedback control. The DC/DC converting circuit includes a switching circuit, a PWM generator and a feedback circuit. The feedback circuit receiving feedback signals reflects an actual output voltage of the switching power supply and transmits the feedback signals to the PWM generator. The PWM generator produces PWM waves to control an on-off time ratio of the switching circuit by comparing the feedback signals with a reference signal that reflects a desired output voltage of the switching power supply. The switching circuit in turn controls the actual output voltage of the switching power supply.